My experience with our 'yurt' matches yours; it just works. However, only the iBook sleeps, the iMac just blacks out the screen. It's running an app that may be contacting the home base several times a night and that may affect how available the internet actually is.
1. Do you know how often Comcast is assigning your IP address?
2. Have you tried entering the DNS server address(es) that Comcast uses in the Network Pref Pane? It's normally an optional entry but if you can find out their address(es), it may be faster than waiting for the Mac to figure it out.
3. Are you leaving any internet accessing apps open during the 'sleep'?
4. Why are your Mac's set to sleep instead of shutdown, anyway? Part of your need for speed?
( see below )
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there is no connection until we wait for, well, an eternity in web-years, say 12-15 seconds. Wanna get on-line quickly? Turn Airport OFF/ON and that will do it, every time.
Me thinks you may need to take some 'patience' pills, anyway. How fast does the AEBS take to run its start up routines? Probably at least 5 - 8 seconds? Add the time to open the Utility and select that option. You're probably saving 3 - 6 seconds!
Just send me your AEBS and I'll check it out for you for a few months!